Mask Fit Testing

Definition - What does Mask Fit Testing mean?

Mask fit testing is a series of steps used to determine the suitability of a respirator mask for a specific user. Each respirator model will fit on the face of a user differently and mask fit testing helps to assure the best and safest fit. The level of suitability of a particular mask is called its fit factor. It is imperative that the individual worker’s respirator mask fit securely in order to protect that worker from respiratory harm in settings where airborne toxins or contaminants are a risk. This test is required by the Occupational Safety and Health Administration (OSHA) before the mask may be used by the individual worker in the workplace.

Mask fit testing may also be known as the mask fit test, respirator fit testing, or simply fit testing.

WorkplaceTesting explains Mask Fit Testing

Mask fit testing requires a series of controlled steps and includes both qualitative (QLFT) and quantitative (QNFT) tests. An individual worker will first be asked to select a mask and make adjustments to its straps until a comfortable but secure fit is attained. The mask should fit tightly enough to create and maintain a full seal around its edges. Once the actual test begins, no further adjustments for fit will be permitted.

During the qualitative test, the test subject is exposed to a non-toxic irritant, the fit test challenge agent, such as smoke. The mask wearer will then be asked to perform a series of exercises including head movements, speaking and breathing deeply. The worker is asked to alert the test monitor if the irritant breaches the seal of the mask during these exercises.

The quantitative test employs a small tube or other device to take air samples from within the face plate during testing. This air sample is then evaluated to determine if, and at what level, the challenge agent was detected within the sealed airspace. Any contaminants detected within the sealed faceplate will lower the mask’s overall fit factor. A mask deemed unsuitable because of a low fit factor may not be used by the subject employee.

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